I use the Jobo 2509 reel in a tank - the reel holds 6 sheets, and the tank takes 270ml, which means that I get three batches = 18 sheets from a 1L kit, so for the 1L kit, using the chemicals one-shot, I get 18 sheets for $65 = $3.61 per sheet. If I use the 5L kit, then I get 18 tank fulls = 108 sheets, so it does bring the cost down to ~$1 per sheet.

Are you not recycling any of the chemicals back into the main storage tank? The tetenal 1L kit is suitable for recycling of chems up to a certain point. That's of course how the 1L kit is able to do 12-16 135 rolls. If I were you I'd really look at reusing the chems after dumping back into the tank for atleast twice the sheets you're doing now.

Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.